1. Field of the Invention
The present invention relates to a pneumatic impact wrench, and more particularly to a bidirectional pneumatic impact wrench with a rotatable air control valve that has two spiral air grooves to direct compressed air to control the direction of rotation of a pneumatic motor in the bidirectional pneumatic impact wrench.
2. Description of Related Art
Pneumatic or air-driven impact wrenches are extensively used to rapidly fasten or loosen bolts or nuts. Most pneumatic impact wrenches generally have an air control valve to direct compressed air and control the direction of rotation of a drive shaft of the pneumatic impact wrench to fasten or loose bolts or nuts.
A rotatable air control valve is convenient to use because a person just needs to rotate the air control valve to change the direction of rotation of the drive shaft. A conventional air control valve in a bidirectional pneumatic impact wrench uses a cylindrical shaft with multiple air slots with different diameters. The air slots are equally spaced along the cylindrical shaft. When operating the air control valve, the air slot with a desired diameter selectively makes a desired air slot communicate with a pneumatic motor of the impact wrench. The airflow of the compressed air is directed and regulated by the desired air slot. However, this kind of air control valve cannot directly reverse the rotation of the pneumatic motor and needs a reversing device to make the rotation of the motor reverse. The conventional air control valve has a complicated structure and only makes  the pneumatic motor rotate in one direction, which raises manufacturing cost.
The conventional cylindrical shaft of the air control valve uses simply air slots with different diameters, which cannot accurately direct and regulate the airflow of the compressed air to make the pneumatic impact wrench output optimum torque.
To overcome the shortcomings, the present invention provides an improved air control valve cylindrical shaft to mitigate or obviate the aforementioned problems.